Light Extrusions is a photography experiment that captures light trails generated from a 3d model. The 3d model is converted to paths using 3d printing software and fed into a 3d printer. Only instead of printing with plastic filament, it uses light from an LED. A camera captures the light using long exposure photography and the results are what you see here.

When MakerBot launched their 5th Generation 3D printers, they introduced the Smart Extruder System. The extruder element is held in place with magnets, making it easy to access filament jams and clogs. However, servicing the extruders themselves was a challenge, sometimes leading to a voided warranty. This project is an attempt to breathe new life into those dead extruders, effectively converting a Smart Extruder into a Light Extruder.

The inspiration for the light extruder came from the works of Ekaggrat Singh Kalsi. The goal was to give anyone with a Makerbot 5th gen printer (and a non functional extruder) the ability to create light extrusions of their own. To do this, I purposely added limitations. First, the printer itself must still operate as a 3d printer. That means any permanent modifications must be done to the lighter extruder only. No custom firmware was allowed but covering light leaks with gaffer tape is fine. Second, all parts must be available for purchase. Any custom 3d files will be available on the light extruder Thingiverse page. A parts list and detailed instructions are currently available there as well.

The Light Extruder
To understand how the light extruder works, you need to understand a little bit about the smart extruder. To feed filament through, there’s a special gear inside the extruder nicknamed the castle nut. The teeth of the gear pulls down filament to a heating element which melts it along a path. The light extruder works by reading in the values coming from the castle nut. If the castle nut is moving in a specific direction, the light will turn on. If it’s moving in the opposite direction or standing still it will turn off. Sounds simple right?

Well actually, not really. Detecting the motions of the castle nut was a little tricky. The only way to do it was to use an optical rotary encoder. It’s a little device that you can attach to an Arduino board to detect when something is rotating. Using Tinkercad, I created a custom mount that sits on top the extruder to house the encoder. Connecting it to the castle nut was a custom ordered round belt.

There has been 2 magical moments I’ve had with 3d printing. The first was when I made my first ever print. The second was the iteration process creating the mount and cog. If something didn’t fit, I made a quick change in model, printed it out in 10 minutes and tested. It’s one thing to debug in software, it’s a completely different experience when debugging something ‘physical’.

ByPassing checks.
The smart extruder has a few sensors built in. Since we are not using filament anymore, the sensors would trigger, preventing the printer from operating. When I worked at MakerBot, I had access to quite a few engineers so figuring out ways to bypass things like filament detection was easy with a little soldering. Bypassing the temperature sensor was a much more difficult problem and would require major electrical and mechanical hacks so leaving it alone was the only solution.

Once I had everything made, it was just a matter of covering all light leaks around the led light. This required boxing the printer and gaffer taping any other light sources on the printer like the extruder spotlight, the display and the LED knobs.

Trial and error.
There were many variables that led to a good capture. The only way to do this was through trial and error. First, the camera had to be light enough to fit on the build plate and small enough to not interfere with the printing process. I originally used an iPhone with apps like Slow Shutter Cam and NightCap Pro to handle the long exposure capture but the results were too inconsistent. Instead I used my m43 camera with a remote for bulb mode. Setting up the 3d model required choosing settings outside the recommendations of the software. Lastly, the LED itself required more precision so a small cheap fiber optic wire was used to dampen and focus the beam of light. Below are some of the calibration settings.

Overall, I’m pretty happy with the results and I will do more light extrusions when time permits.